Sensor assembly

Abstract

A flow sensor assembly comprising a first substrate, a flow sensor located over the first substrate, a lid located over the first substrate and the flow sensor, a flow inlet channel, a flow outlet channel, and an overmold laterally encircling the flow sensor. The overmold is in contact with the side walls of the flow sensor, and extends between the flow sensor and the lid such that the overmold, the flow sensor, and the lid define a flow sensing channel between the flow inlet channel and the flow outlet channel. the lid and the encapsulation cooperate to define the flow inlet channel and the flow outlet channel.

1 . A flow sensor assembly comprising:
 a first substrate;   a flow sensor located over the first substrate;   a lid located over the first substrate and the flow sensor;   a flow inlet channel;   a flow outlet channel; and   an overmold laterally encircling the flow sensor and in contact with the side walls of the flow sensor, wherein the overmold extends between the flow sensor and the lid such that the overmold, the flow sensor, and the lid define a flow sensing channel between the flow inlet channel and the flow outlet channel, and   wherein the lid and the encapsulation cooperate to define the flow inlet channel and the flow outlet channel.   
     
     
         2 . A flow sensor assembly according to  claim 1 , wherein the flow sensing channel comprises sloped sidewalls formed by the overmold; and/or
 wherein the overmold is disposed at least partly over a top surface of the flow sensor.   
     
     
         3 . A flow sensor assembly according to  claim 1 , further comprising electrical contacts coupling the flow sensor to the first substrate, and wherein the electrical contacts are encapsulated within the overmold. 
     
     
         4 . A flow sensor assembly according to  claim 1 , wherein a first surface of the overmold is substantially level with a surface of the sensor. 
     
     
         5 . A flow sensor assembly according to  claim 1 , wherein the flow channel comprises one or more channel restrictors, and optionally wherein the one or more channel restrictors is located above the flow sensor. 
     
     
         6 . A flow sensor assembly according to  claim 1 , further comprising one or more guide structures located between the flow inlet channel and the flow outlet channel. 
     
     
         7 . A flow sensor assembly according to  claim 1 , wherein the lid comprises a recess, and
 wherein the recess, the overmold, and the flow sensor define the flow channel through the flow sensor assembly.   
     
     
         8 . A flow sensor assembly according to  claim 1 , further comprising an additional flow channel formed by at least one further recess or aperture within the overmold and/or the lid; and
 optionally wherein said additional flow channel is substantially parallel to the flow sensing channel; and/or
 wherein said additional flow channel has a substantially larger cross-sectional area than the flow sensing channel. 
   
     
     
         9 . A flow sensor assembly according to  claim 1 , wherein the overmold and/or the lid are configured such that the flow inlet channel and/or the flow outlet channel have a larger cross-section than the flow sensing channel, and optionally
 wherein a cross-sectional area of the flow inlet channel and/or the flow outlet channel tapers from a surface of the flow sensor assembly towards the flow sensing channel.   
     
     
         10 . A flow sensor assembly according to  claim 1 , further comprising one or more spacers having a first surface located within 50 μm of a surface of the flow sensor or a surface of the first substrate, and a second surface in contact with a first surface of the lid, wherein the first surface of the lid faces the flow sensor and the first substrate. 
     
     
         11 . A flow sensor assembly comprising:
 a first substrate;   a flow sensor mounted on a first surface of the first substrate;   a lid located over the first substrate and the flow sensor;   a flow inlet channel;   a flow outlet channel, wherein a surface of the flow sensor and a surface of the lid cooperate to form a flow sensing channel between the flow inlet channel and the flow outlet channel; and   a spacer having:
 a first surface located within 50 μm of a surface of the flow sensor or a surface of the first substrate; and 
 a second surface in contact with a first surface of the lid, wherein the first surface of the lid faces the flow sensor. 
   
     
     
         12 . A flow sensor assembly according to  claim 11 , wherein the first surface of the spacer is in contact with a top surface of the flow sensor or a top surface of the first substrate, and wherein the top surface of the flow sensor or the top surface of the first substrate faces the lid. 
     
     
         13 . A flow sensor assembly according to  claim 11 , wherein a second surface of the lid is in contact with a second surface of the first substrate, by way of an adhesive, and wherein the second surface of the lid faces the same direction as the first surface of the lid; and
 optionally wherein the second surface of lid comprises one or more recesses configured to receive the adhesive; and
 optionally wherein one or more recesses comprise an aperture within a sidewall of the recess. 
   
     
     
         14 . A flow sensor assembly according to  claim 11 , wherein the first surface of the spacer is in contact with a top surface of the flow sensor, wherein the top surface of the flow sensor faces the lid, and wherein a bottom surface of the flow sensor is in contact with the first surface of the first substrate, by way of an adhesive, wherein the first surface of the first substrate faces the lid. 
     
     
         15 . A flow sensor assembly according to  claim 11 , wherein the one or more spacers extend from a first inside edge of the lid to a second inside edge of the lid; and/or
 wherein the one or more spacers is monolithic with the lid   
     
     
         16 . A flow sensor assembly according to  claim 11 , wherein the one or more spacers is configured to be within 50 μm of at least one side surface of the flow sensor; and
 optionally wherein the one or more spacers is in contact with at least one side surface of the flow sensor; and/or
 wherein the first surface of the one or more spacer is chamfered. 
 
 
     
     
         17 . A flow sensor assembly according to  claim 1 , wherein the flow sensor comprises:
 a sensor substrate comprising an etched portion;   a dielectric layer located on the sensor substrate, wherein the dielectric layer comprises at least one dielectric membrane located over the etched portion of the sensor substrate; and   a sensing element located on or within the dielectric membrane; and
 optionally wherein the first substrate defines an aperture. 
   
     
     
         18 . A flow sensing system comprising:
 a main channel extending in a first direction;   a flow sensor assembly according to  claim 1 , wherein the flow sensor assembly is located in the main channel such that the flow sensing channel of the flow sensor assembly is substantially parallel to the main channel.   
     
     
         19 . A method of manufacturing a flow sensor assembly, the method comprising:
 forming a first substrate;   forming a flow sensor located over the first substrate;   forming a lid located over the first substrate and the flow sensor;   forming a flow inlet channel;   forming a flow outlet channel;   forming an overmold laterally encircling the flow sensor and in contact with the side walls of the flow sensor, wherein the overmold extends between the flow sensor and the lid such that the overmold, the flow sensor, and the lid define a flow sensing channel between the flow inlet channel and the flow outlet channel, and wherein the lid and the encapsulation cooperate to define the flow inlet channel and the flow outlet channel.   
     
     
         20 . A method of manufacturing a flow sensing system, the method comprising:
 providing a main channel extending in a first direction;   manufacturing a flow sensor assembly according to the method of  claim 19 ;   positioning the flow sensor assembly within the main channel such that the flow sensing channel of the flow sensor assembly is substantially parallel to the main channel.